Alloy steel



Patented Sept. s, 1935 awor PATENT OFFICE STEEL- Walter Grafts, NewYork, N.- 1., assignor to a...

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This invention relates to sulfur-bearing steels, more especiallyreferring to improvements in such steels, and the immediate object of myinvention is to produce a superior free-machining 81111111 steel.

The presence of sulfur in amounts appreciably greater than thoseconsidered desirable in structural and engineering steels is known to beadvantageous from the standpoint of ease of me.- 10 chining. Screw stockfor example is cus produced with a sulfur content of about 0.10%, ascontrasted with the upper limit of about 0.050% usually specified forengineering'steels. Despite their desirable machining characteristicshowever, the high sulfur steels are strictly limited in theirapplication, for when made by methods heretofore known they are notsuitable for general engineering uses. 1 A superior freemachining highsulfur steel is not only of value in the present field of application,since it pro-' vides a uniform and reliable-engineering ma terial, butalso extends that field to many other uses where its desirable machiningcharacteristics lead to savings in fabrication and finishing costs.

I have discovered that asuperior high sulfur steel may be produced bythe alloyed addition of proper amounts of vanadium. According to thepreferred embodiment of my invention, from about 0.05% to about 1% ofvanadium is added to a steel containing from about 0.075% to about- 0.5%of sulfur to produce steel of superior machining and physicalproperties. The presence of vanadium in these amounts improves themaworking characteristics, and decreases the size- ,and effects a moreuniform distribution of the sulfide inclusions in the steel withoutdecreasing the ductility or shock resistance, as is shownby physicaltests-and microscopic examination.

The addition of vanadium in amountsother than those within the preferredrange are of some benefit to the properties of sulfur'steels, but lessthan 0.05% has only a slight effect, while the use of more than about0.5% is inadvisable chiefly because the added'expense of the vanadiumofi'sets the advantages to be gained by the use of a greater amount.Furthermore, al-' though the addition of vanadium appears to benefit thesulfide distribution in all sulfur steels, the free-machining sulfursteels as a class come within the range of sulfur content given above,and therefore m'yainvention is most profitably to be applied to steelswithin this range. 1 Taste which I have made demonstrate clearly theimprovement effected by the addition of.

chining properties, improves the hot and cold Company, a corporation ofOctober 17. 1931, 589,548

(01. 15-1) vanadium. For example, typical high sulfur 1 steelscontaining about 0.11% of sulfur, 1.2% of manganese and 0.15% of carbonwere compared with similar-steels containing as an alloyed aodition fromabout 0.05% to about 0.35% of 5 vanadium. It was found that the presenceof vanadium effected a marked improvement in sulfide-inclusion size anddistribution, and improved the' machining characteristics remarkably.Further tests on these samples demon- 10 I 0.30% of-carbon, about 1.5%of chromium, al- 20.

loyed additions of vanadium up to about 0.5%, and the remainder chieflyiron, has remarkably good machining properties in addition to excellentand valuable physical properties which render it valuable forengineering uses. The steels of the present invention contain the smallamounts of carbon, silicon, phosphorus. etc. usually contained asincidental impurities in Although I have described the preferred form 30of my invention, and have mentioned certain specific typicalembodiments, it will be understood that my invention pertains to alloysulfur steels generally.

' 1. An alloy steel characterized by propertie of free-machinability andhigh strength, and which contains sulphur, vanadium, manganese, andcarbon, the sulphur content being from about 0.075% to about 0.5%. thevanadium con- 40 tent being'from about 0.05% to about 1.0%, the,manganese content being not over about 1.25%, thecarbon content beingnot over 0.5%, and the remainder, except for incidental impurities,being iron.

2. An alloy steel characterized by properties of free-machinability andhigh strength, and which contains sulphur, vanadium, manganese. andcarbon, the sulphur content being from free-machining sulphur steels.

' about 0.075% to about 0.5%, the vanadium content being from about0.05% to about 0.50%, the manganese content being not 'over about 1.25%,the carbon content being not over 0.5%, and the remainder, except forincidental impuri-

